"An investigation to determine the structural damping characteristics of a full-scale airplane wing was conducted by the shock-excitation method wherein the wing was loaded to a predetermined deflection and the load suddenly released. The test specimen vibrated at its fundamental bending frequency of 1.69 cycles per second. Only the first 2 or 3 cycles showed any indication of a higher frequency being superimposed upon the fundamental bending frequency. The damping was found to increase from about 0.002 to critical at an amplitude of vibration of plus and minus 0.05 inch to approximately 0.006 of critical at an amplitude of + or - 5 inches" (p. 1).

"A coincidence Geiger counter system was constructed for the absolute measurement of the activity of radioactive substances made in a cyclotron. The average beam current in the cyclotron can be calculated from the number of disintegrations per second observed, the half-life of the radioactive substance, and the reaction cross section" (p. 1).

Report presenting the use of molybdenum disulfide as a solid film lubricant in applications where designs or temperatures preclude liquid lubricants is dependent on successful bonding of the powder to the surface to be lubricated. An investigation was conducted to determine the basic mechanism of bonding and to extend application of the bonding to a variety of materials. Results regarding an examination of electron diffraction of MoS2 dusted and rubbed on steel, adherence of dry powders to metals, chemical action in bonding mechanism, other resin-forming liquid vehicles, bonding of MoS2 and other powders to various materials, and analysis of solid film by electron diffraction are provided.

Note presenting tests to determine local heat-transfer coefficients and friction factors for fully developed turbulent flow of air in a smooth electrically heated tube with an inside diameter of 0.87 inch and a length of 87 inches. Testing occurred at high ratios of wall to fluid bulk temperatures. Results regarding the predicted temperature and velocity distributions, Nusslet numbers, friction factors, velocity distributions, and temperature distributions are provided.

Note presenting a survey of the chromium-cobalt-nickel ternary phase diagram at 1200 degrees Celsius by means of microscopic and X-ray diffraction studies on 110 vacuum-melted alloys prepared from commercial metals of the highest purity available. Three distinct phases are noted.

Note presenting a discussion of a semiempirical profile correction factor which enables the estimation of the wave drag due to thickness at supersonic speeds for three-dimensional wings with arbitrary airfoil section through use of previously calculated drag coefficients. Application of the correction factor to the known drag coefficients of some rhombic-profile wings yielded estimates for the drag coefficients of parabolic-arc-profile wings that were in good agreement with theoretically calculated values.

"An isothermal survey was made of certain portions of the chromium-cobalt-nickel-iron quaternary system at 1200 degrees Celsius. The iron content was varied up to 30 percent to include the range of commercial chromium-cobalt-nickel alloys. As a part of the quaternary system, the cobalt-chromium-iron ternary system was also studied" (p. 1).

Note presenting the principle of complementary energy in the nonlinear elasticity theory, which is shown to be derivable from the principle of potential energy by a Legendre type of transformation. The expression of the complementary energy is derived for homogeneous and sandwich plates and shells with large deflections. The stress-strain relations are derived for homogeneous shells, sandwich plates, and sandwich shells.

Report presenting a study in which heavy hydrogen (deuterium) was substituted in turn for regular hydrogen in each of five possible hydrogen-producing operations in the coating process. The gas that evolved when coated steel specimens fishscaled after firing was collected and analyzed with the mass spectrometer.

Note solving basic equations of Karman and Chien by representing the shape of a torsion box by means of a Fourier series. The coefficients of the series are determined by conventional methods. Results obtained for angles of twist and normal stresses are in good agreement with results of Karman and Chien except at sharp corners.

Report presenting normal accelerations and airspeed data collected with NACA V-G recorders in transport airplane operations from 1933 to 1945, which are summarized and analyzed with respect to gusts and gust loads. The accelerations experienced in most operations equaled or exceeded the limit-gust-load-factor increment, on average, twice in 107 flight miles. Results regarding the acceleration experience, gust experience, probable airspeed, and maximum airspeed are provided.

Note presenting bending-moment distributions that were measured on a model helicopter rotor blade under hovering and simulated forward-flight conditions. curves of maximum-bending-moment distribution are presented for all test conditions. Resonance studies have also been made on three sets of blades of different stiffnesses for the purpose of comparing the experimentally determined resonance peaks with those indicated by theory.

Report presenting a solution of the Navier-Stokes equation for source and sink flows of a viscous, heat-conducting, compressible fluid for the case of constant total flow energy.

From Introduction: "The problem of free-convection flow as produced by a body force about a flat plate in the direction of the body force was studied at the NACA Lewis laboratory and is treated in a formal and more general manner herein. The method used is somewhat similar to that used in reference 4 wherein consideration was given to the free-convection flow at high Grashof numbers in a horizontal cylinder which had a variable surface-temperature distribution. In addition, the numerical solutions of references 2 and 3 are herein extended to cover a more complete range of variables."

Report presenting an experimental investigation of the effect of oil viscosity on bearing operation characteristics using a 75-millimeter-bore cylindrical-roller inner-race-riding cage-type bearing. Results regarding DN value, oil flow, viscosity, the combination of DN and oil flow, oil inlet temperature, and improvements to cooling correlation theory are provided.

Note presenting a theoretical solution obtained for the problem of the compressive buckling of flat rectangular Metalite type sandwich plates with simply supported loaded edges and clamped unloaded edges. The solution is based on the general small-deflection theory for flat sandwich plates developed in a previous NACA report. Results regarding the stability criterion and buckling curves, correction for plasticity, and a comparison with theoretical results are provided.

From Summary: "Results of an analytical and a sea-level experimental investigation of a turbojet engine with proportional speed control are presented."

Report presenting the use of the similarity law for steady hypersonic flow about slender shapes as extended to nonsteady flows. The aerodynamic forces and moments are correlated for related shapes by means of this law. The motions of related bodies in free flight could be correlated using the hypersonic similarity parameters and additional parameters relating the inertial properties of the bodies and air densities.

"The corrosion resistance of unprotected magnesium-zinc-zirconium alloy ZK60A was determined in a marine atmosphere and in tidewater. The unprotected alloy was so rapidly attacked in tidewater that it would be of no practical value in applications subject to wetting by sea water. In the marine atmosphere the rate of corrosion was much less and the alloy should give good service if adequately protected" (p. 1).

Report presenting some preliminary calculations for airplanes of current design in order to determine the proper angles of sideslip in order to design ideal vertical tails. Existing simplified calculations for determining these values are not generally applicable to airplanes of current design, but a new solution is proposed. Results for two different airplanes are provided and suggestions for adjusting calculated sideslip values are provided.

Report presenting transient data from approximate step and sinusoidal disturbances of fuel flow on a turbojet engine operated at one constant simulated altitude and flight condition. Results regarding coefficients of differential equations, Fourier representation, frequency response, transient analysis, and a comparison of the various analytical methods are provided.

Report presenting results of axial-load fatigue tests on notched specimens of three sheet materials: 24S-T3 and 75S-T6 aluminum alloys and normalized SAE 4130 steel. Tests were run at four levels of nominal mean stress.

"Several common methods for curve fitting a set of data by least squares are described and evaluated. The methods are evaluated by applying them to an example taken from aerodynamics: the problem of calculating the stability parameters of an airplane from flight data. There are other points considered: application of the methods to minimization problems other than curve fitting and the question of convergence to a mere stationary point as opposed to convergence to a minimum" (p. 1).

Report presenting supersonic profiles of minimum pressure drag for a given thickness ratio and a given area created by using non-linear pressure relation and compared with minimum-drag profiles found by linearized theory. The parameters determining the airfoil shape for a given thickness ratio found by linear and nonlinear theory are presented in graphs as a function of the base pressure coefficient.